FSM oil pressure

[krayton]

Ok just trying to get this solved and taken care of.

Now im not looking for what your oil pressure is. Im trying to find what nissan wanted there RBs to be "approx" according to the fsm



ok, so im looking at rb25

conversion wise, i think somethings up with KPa. Maybe a mis translate?

but from what im guessing:

@ idle: Approx = 1 bar/14.7psi@2000: Approx = 3.5 bar/50.7psi@6000: Approx = 5.6bar/81.2psi

Anyone wanna chime in? Obviously the fsm says "approx." we know different weight oil changes it. and im assuming these pressures are hot

[disrupt]

bar and kg/cm2 are not the same. they are very close though. your numbers are right in PSI within about 2% on the high side.

[gawdzilla]

there is something wrong with the KPa they've listed. it's on the order of x1000 off. that should read Approx. 100{1.0}, 340{3.5}, 550{5.6} for the RB25DET. So that ends up being 14.2-14.5 psi, 49.3-49.8psi, 79.7-79.8psi depending on which unit you are converting to PSI.

The numbers in that chart you posted (from R33 engine manual?) matches the R32 GT-R FSM for the RB26DETT as well. For the RB26, it says the reading should be taken at Oil temperature 80 C or 176F, using the recommended oil 7.5w30, which I assume is between 5w30 and 10w30.

For the 25, the oil temp and oil type for the reading should be the same I believe.
Modified by gawdzilla at 7:35 PM 5/25/2009

[eh?]

Did you figure out your oil pressure problem?

[GTRs13]

What problem is it? On what RB?

I though the Krayton just needed the values of the FSM.

Hey Eh? , I just got banned for a week for having the rb forums link in my sig. You might want to take care of that.

[krayton]

Did you figure out your oil pressure problem?

hah, never. my built engine has some bad bearings. got a new crank for it.

so, while im waiting, got a brand new used block. comps test great, but after my 1st track event, my oil was bouncing near 12-16psi. of course this is in 100degree az heat and no oil cooler. also running 0w-20 royal purple.

but yeah, i swear these oil problems will just keep following me around. at this point im thinking its ok. research on the aussie boards showed idle pressure isnt that important as long as you have it. more important is the pressure at mid and high rpm which it has.

uggggggg

edit always on rb25s. my problems are on built blocks but i found out the issue. this current one is a stock rb25 though.

[krayton]

if it wasnt from my track day, i would of never known about it. if i drive it around town my oil pressure never goes below 1bar. can only guess i actually got my oil up to a hot temp.

[mattblancarte]

so, while im waiting, got a brand new used block. comps test great, but after my 1st track event, my oil was bouncing near 12-16psi. of course this is in 100degree az heat and no oil cooler. also running 0w-20 royal purple.

Are you monitoring your oil temps? I wouldn't be surprised if you're slowly frying your bearings... Anything over 110 degrees C is bad.
Modified by mattblancarte at 1:03 PM 5/26/2009

[eh?]

How much pressure did you have at idle with the built block?

I just redid my block, oil pressure with 5w-20 oil sits around 12psi at idle after driving for a while. Seems to never want to get above 55psi at high rpms. I did pull apart the oil pump to inspect and the gears could use a replacement but it does have a bit less pressure than before.

But honestly with the ACL bearings having looser clearances and the lighter weight oil I'm not too concerned. After breakin I plan on going with a thicker 20w-50 to see how it works out.

[krayton]

^

matt: my crapped apexi el2 gauge for oil temp crapped out, so i have no clue. im working on getting another and havent installed my big a** oil cooler yet.

eh, i think when my engine was on the dyno, i was just at 1bar. that was with 20w-50. but there is so much wierd info on oil pressure out there. like i said, i think its just important at different rpms. but i think near redline you should be near 60+psi. and iirc the relief valve is 80psi

edit: i do find most people saying add 10 psi for every 1000rpm on top of your idle psi

[mattblancarte]

I pay very very close attention to my temps and pressures. Here are my norms:

Cold-start idle (after it simmers down to 900rpm): 50-60 psiWarm idle: 25-30 psiWarm at 3000 rpm: 60 psiWarm at 6000 rpm: 90 psiWarm at 7500 rpm: 95-100 psi

I use motul chrono 300v 10w-40.

I wouldn't track your car (in AZ hotness) unless you can monitor temps and pressures for both oil and coolant.

p.s. I say this with experience in AZ. I ran there all in 2008-2009 during both the hot and cold season.

[mattblancarte]

edit: i do find most people saying add 10 psi for every 1000rpm on top of your idle psi

This is like the minimum rule of thumb for track use. I wouldn't be happy with only 60 psi of pressure...

[eh?]

This is like the minimum rule of thumb for track use. I wouldn't be happy with only 60 psi of pressure...

You gotta remember pressure is the resistance to flow. Higher pressure isn't always better and is why I'm not very concerned.

[krayton]

yeah, high pressure can actually be bad.

matt what kind of pump do you have? i thought the relief valve was 80psi.

[mattblancarte]

You gotta remember pressure is the resistance to flow. Higher pressure isn't always better and is why I'm not very concerned.

Higher pressure may not always be better, but it means that you're pushing more oil through to create that resistance.

Some of the higher-performance oil pumps like tomei, greddy, etc. all flow over 100psi at redline. I think the tomei pump is rated at 110+ psi.

matt what kind of pump do you have? i thought the relief valve was 80psi.

OEM bnr34 rb26 pump.

My pressure may be a bit higher than yours due to my oil cooler (extra lines for the oil to travel through) and the weight of oil I use, but still, you should be up in the 75 psi range at redline.

[gawdzilla]

comps test great, but after my 1st track event, my oil was bouncing near 12-16psi. of course this is in 100degree az heat and no oil cooler. also running 0w-20 royal purple.

that is normal, given an oem pump, hot oil temps (probably 240F+ I'm guessing with just the factory oil to water cooler), and 0w-20. Not saying it's good for the motor, but that is expected given your conditions and oil weight.

[maryjane]

i have a JUN oil pump, acl race bearings and rotella 15w-40 and i see 110-115 psi at 8500-9000 rpm, between 40-55 psi warm idle, cold idle 80-95psi